Published 10:39 am, Thursday, May 16, 2013

To make the stem cells, they had to let the embryo reach the balstocyst stage before destroying it to extract the stem cells and grow them in the lab.

The cells can then be turned into any different kind of cell, and used to produce new tissues that would be genetically identical to the person whose genome was inserted into the egg.

The research "will lead inexorably to cloning to produce a live born child," said bioethicist O. Carter Snead, of the University of Notre Dame, told Reuters.

The researchers who performed the new study say that's just not true.

"Reproductive cloning hasn't been advanced by this new paper," Rudolf Jaenisch of the Massachusetts Institute of Technology told Reuters. "If you implanted these embryos, which would be illegal, I think you would get the same results as in mice: Most of them die at birth, and the others encounter big troubles as they age."

California banned reproductive cloning in 1997. Since then about a dozen states have followed suit. Six states also ban therapeutic cloning.